What type of drill bits do you need for plastic?

By: HowStuffWorks.com Contributors  | 

While drilling through plastic can be done using any power drill, it’s important to have the correct drill bits so you don’t chip or crack the material. Irregular holes and rough edges could lead to cracking, even months after the drilling occurs. Drill bits for plastic are available in a variety of sizes; however, it’s best to consult with a professional before undertaking a project on your own.

When drilling plastic, the larger the hole, the slower drill speed you should use since high speeds can melt the plastic. Also, always reduce the drill speed as the drill bit exits the material. Before drilling, it’s best to clamp down the plastic securely to a solid surface and back up the piece you are drilling with a spare piece of plywood underneath. This way the drill bit enters the plywood when it exits the plastic and avoids chipping the surface on the bottom.

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In addition, it’s recommended to use a lubricant while drilling deeper holes to help remove debris and dissipate the heat. Furthermore, since plastics expand and contract with temperature changes, make sure you drill a slightly larger hole than necessary to allow room for screw movement without placing stress on the material.

The most effective drill bits for plastics are spur-point bits, also known as dowel bits. They are specifically angled to make smooth cuts in the material. A spur-point bit has a central point and spurs that keep the bit aligned, maintaining a clean, neat hole. Some soft materials, including plastics, benefit from countersinking before actually drilling. A power drill is used to countersink or create a depression in the material first. Using a countersink bit along with a plastic drill bit ensures that the drill bit remains in the center of the depression. Never use twist bits when drilling plastics; they can splinter and ruin the material.

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Originally Published: Jul 25, 2011

Best Drill Bit for Plastic FAQ

What drill bit is best for plastic?
Spur-point drill bits (dowel bits) are best suited for drilling holes in plastic. The point and angle in front of these bits ensure that the stress in front is minimized and that the cut is smooth. We recommend slowing down as you are exiting to get a clean and neat hole.
Can you drill through acrylic?
You can drill through acrylic. Just drill slowly, make sure that whatever you're drilling into is supported and consider using a lubricant.
What material are drill bits made of?
Drill bit material differs based on their intended use. For example, some bits are made of high-speed steel (HSS). These bits are useful for softer steels, plastic and wood. There also are wood, plastic and even cobalt bits.
Will a spade bit drill through plastic?
If you have to use a spade bit to drill a hole through plastic, we recommend you go slow and be very careful. You might have to sand the edges once you are done.
How do you drill holes in plastic?
When drilling plastic, the larger the hole, the slower drill speed you should use since high speeds can melt the plastic. Also, take care to reduce the drill speed as the drill bit exits the material. Before drilling, it’s best to clamp down the plastic securely to a solid surface and back up the piece you are drilling with a spare piece of plywood underneath.
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